Translating dual axis adjustable interbody fusion spinal system

ABSTRACT

An interbody fusion device employs a torque transfer mechanism to transfer torque to a driving mechanism responsible for expansion of the interbody fusion device in a direction non-parallel to a longitudinal axis of the driving mechanism.

TECHNICAL FIELD

This disclosure relates in general to apparatuses, systems, and methodsfor treating spinal diseases. In particular, various embodiments ofexpandable and adjustable lordosis interbody fusion devices aredescribed.

BACKGROUND

Spinal fusion is a surgical procedure to correct problems relating tothe human spine such as degenerative disc disease (DDD),spondylolisthesis, recurrent disc herniation, etc. It generally involvesremoving damaged disc and bone from between adjacent vertebrae andinserting bone graft material that promotes bone growth. As the bonegrows, the adjacent vertebrae join, or fuse, together. Fusing the bonestogether can help make that particular area of the spine more stable andhelp reduce problems related to nerve irritation at the site of thefusion. Fusions can be done at one or more segments of the spine.

In an interbody spinal fusion procedure, the nucleus pulposus and/or theannulus fibrosus that compose the intervertebral disc at the point ofthe damage are removed and an implant configured in shape and dimensionis placed in the disc space to restore the distance between adjacentvertebrae to a proper condition. Surgical approaches to implementinterbody fusion vary, and access to the patient's vertebral column canbe made through the abdomen or back. One surgical method foraccomplishing lumbar spinal fusion in a less invasive way involvesaccessing the vertebral column through a small incision on the posteriorside where the surgeon removes a portion of bone and joint at the backand side of the vertebrae. These sections of bone and joint are called,respectively, the lamina and the facet joint. This procedure is known astransforaminal lumbar interbody fusion (TLIF). The transforaminaltechnique allows the surgeon to insert bone graft and spacer into thedisc space from a unilateral approach laterally without having toforcefully retract the nerve roots, which can reduce injury and scarringaround the nerve roots as compared to the more traditional posteriorlumbar interbody fusion procedure (PLIF), which requires nerve rootretraction and a bilateral approach. Other common surgical methods orapproaches for reaching the desired intervertebral disc of concern arethrough access of the anterior and/or anterolateral column of the spine.Lateral lumbar interbody fusion (LLIF) is a minimally invasive procedurein which the surgeon accesses the spine through a small surgicalincision in the side with dissection of the psoas muscle or navigationaround the psoas muscle, also known as anterior-to-psoas lateral lumbarinterbody fusion (ATP LLIF). LLIF and ATP LLIF procedures allow fordelivery of larger interbody fusion device footprints with minimaldisruption of the patient's anatomy, along with the ability to performindirect decompression of the nerve root elements. Anterior LumbarInterbody Fusion (ALIF) is a procedure in which the surgeon accesses thedesired intervertebral disc of concern through an open incision in theabdomen navigating through the abdominal muscles as well as bypassingorgans and vascular structures. ALIF procedures allow for delivery oflarger interbody fusion devices in comparison to any other interbodyfusion procedure, which in turn provide good indirect decompression andrisk against subsidence or sinking of the delivered implant into thevertebral body elements.

Conventionally, once the intervertebral disc is removed from the body,the surgeon typically forces different trial implants between thevertebral bodies of the specific region to determine the size of theimplant for maintaining a proper distance between the adjacentvertebrae. A proper angle between the vertebral bodies also must bemaintained to accommodate the natural curvature of the spine e.g. thelordosis. Therefore, during selection of a fusion device forimplantation, both intervertebral disc height and lordosis must beconsidered. Traditional implant devices are often pre-configured to havetop and bottom surface angles to accommodate the natural curvature ofthe spine. It is unlikely or difficult that these values can bedetermined precisely prior to the operation. Further, in implementing atrial-and-error approach to sizing and fitting the interbody fusiondevice into the target region for geometric configuration, the patientis subjected to significant invasive activity. If a hyperlordoticsagittal profile configuration (≥20°) is set or supplemental fixationfor the lumbosacral levels is desired, the surgeon may place a spinalconstruct in the form of anterior column fixation such as an additionalplate and screw assembly to prevent possible movement or migration ofthe fusion device in the intervertebral disc space and/or to providetemporary stabilization of the anterior column of the spine during thespinal fusion process until arthrodesis takes place. This can requirethe surgeon to perform a secondary surgery after placing the fusiondevice, which in turn would lengthen the overall surgery time leading tomore potential blood loss and complications with anesthesia for thepatient.

SUMMARY

An example interbody fusion device comprises a housing, a drivingmechanism operable to expand and/or contract the housing, and a gearassembly operable to transfer torque to the driving mechanism. Thedriving mechanism comprise an axle having a longitudinal axis. The gearassembly comprises a first translating gear coupled to the axle and afirst driving gear configured to receive torque applied from a directionnon-parallel to the longitudinal axis of the axle and drive the firsttranslating gear, whereby application of torque to the first drivinggear causes the first translating gear and the axle to rotate about thelongitudinal axis, thereby actuating the driving mechanism to effectexpansion and/or contraction of the housing.

An example interbody fusion device comprises a housing, a first drivingmechanism, a second driving mechanism, a first gear assembly, and asecond gear assembly. The first driving mechanism is arranged in thehousing at a first lateral area. The second driving mechanism isarranged in the housing at a second lateral area. The first drivingmechanism comprises a first axle having a longitudinal axis. The seconddriving mechanism comprises a second axle having a longitudinal axis.The first gear assembly is operable to transmit torque to the firstdriving mechanism. The first gear assembly comprise a translating gearcoupled to the first axle and a driving gear configured to receivetorque applied from a direction non-parallel to the longitudinal axis ofthe first axle and drive the translating gear, whereby application oftorque to the driving gear causes the translating gear and the firstaxle to rotate about the longitudinal axis of the first axle, therebyactuating the first driving mechanism to effect expansion and/orcontraction of the housing at the first lateral area. The second gearassembly is operable to transmit torque to the second driving mechanism.The second gear assembly comprises a first translating gear coupled tothe second axle and a first driving gear configured to receive torqueapplied from a direction non-parallel to the longitudinal axis of thesecond axle and drive the first translating gear, whereby application oftorque to the first driving gear causes the first translating gear andthe second axle to rotate about the longitudinal axis of the secondaxle, thereby actuating the second driving mechanism to effect expansionand/or contraction of the housing at the second lateral area.

This Summary is provided to introduce selected embodiments in asimplified form and is not intended to identify key features oressential characteristics of the claimed subject matter, nor is itintended to be used as an aid in determining the scope of the claimedsubject matter. The selected embodiments are presented merely to providethe reader with a brief summary of certain forms the invention mighttake and are not intended to limit the scope of the invention. Otheraspects and embodiments of the disclosure are described in the sectionof Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

These and various other features and advantages of the disclosure willbecome better understood upon reading of the following detaileddescription and the appended claims in conjunction with the accompanyingdrawings, where:

FIGS. 1A-1D depict an example interbody fusion device according toembodiments of the disclosure. FIG. 1A is an isometric view, FIG. 1B atop view, FIG. 1C a partially exploded view, and FIG. 1D across-sectional view.

FIGS. 2A-2C depict an example interbody fusion device of the disclosurein conjunction with a surgical instrument. FIG. 2A is a perspectiveview, FIG. 2B a close-up perspective view, and FIG. 2C is a close-upside view.

FIGS. 3A-3D illustrate engagement of an example dual-axis interbodyfusion device of the disclosure with a surgical instrument in variousoperating modes. FIG. 3A is a cross-sectional view emphasizing a firstdriver and a second driver of a surgical instrument, FIG. 3B across-sectional view showing engagement of an interbody fusion devicewith a surgical instrument in an expansion mode (simultaneous dual-axisadjustment), FIG. 3C a cross-sectional view showing engagement of aninterbody fusion device with a surgical instrument in a lordosis mode(independent anterior axis adjustment), and FIG. 3D a cross-sectionalview showing engagement of an interbody fusion device with a surgicalinstrument in another lordosis mode (independent posterior axisadjustment).

FIG. 4 is a partially exploded view of an example interbody fusiondevice illustrating simultaneous adjustment of both sets of drivinggears and axles (simultaneous dual-axis adjustment) of the interbodyfusion device together in turn driving both translating axles togethercreating a parallel expansion operating mode.

FIG. 5 is a partially exploded view of an example interbody fusiondevice illustrating independent operation of only the driving gears andaxles within the second lateral portion (independent anterior axisadjustment) of the interbody fusion device in turn driving only thetranslating axle in the second lateral portion of the interbody devicecreating unequal expansion or a lordosis operating mode.

FIG. 6 is a partially exploded view of an example interbody fusiondevice illustrating independent operation of only the driving gears andaxles within the first lateral portion (independent posterior axisadjustment) of the interbody fusion device in turn driving only thetranslating axle in the first lateral portion of the interbody devicecreating unequal expansion or a lordosis operating mode.

FIG. 7 depicts an example interbody fusion device in an expandedconfiguration.

FIG. 8 depicts an example interbody fusion device in a lordoticallyadjusted configuration.

FIGS. 9A-9B depict an example interbody fusion device placed betweenadjacent vertebrae. FIG. 9A is an anterior view, and FIG. 9B a lateralview.

FIGS. 10A-10B depict an example interbody fusion device and a fixationassembly according to embodiments of the disclosure. FIG. 10A is anexploded view, and FIG. 10B an assembled view.

FIG. 11 depicts an example fixation plate according to embodiments ofthe disclosure.

FIGS. 12A-12B depict attachment of an example fixation plate to anexample interbody fusion device according to embodiments of thedisclosure. FIG. 12A is an exploded view, and FIG. 12B an assembledcross-sectional view.

FIGS. 13A-13B depict attachment of another example fixation plate to anexample interbody fusion device according to embodiments of thedisclosure. FIG. 13A is an exploded view, and FIG. 13B an assembledcross-sectional view.

FIGS. 14A-14C illustrate attaching of an example fixation plate to anexample interbody fusion device and securing of the interbody fusiondevice to adjacent vertebrae using a surgical instrument.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the figures, where like reference numerals denote likeparts, various embodiments of an interbody fusion device will now bedescribed. It should be noted that the figures are only intended tofacilitate the description of embodiments and not as an exhaustivedescription or a limitation on the scope of the disclosure. Further,certain specific details are shown in the figures in order to provide athorough understanding of various embodiments of the disclosure. Oneskilled in the art will understand that the claimed invention can bepracticed without these details. In other instances, well-knowncomponents, structures, or steps associated with the devices and methodsof the disclosure may not be shown or described in detail to avoidunnecessarily obscuring the description of embodiments of thedisclosure. It should also be noted that certain aspects or featuresdescribed in conjunction with a particular embodiment are notnecessarily limited to that embodiment and can be practiced in any otherembodiments.

In general, various embodiments of an interbody fusion device comprise adriving mechanism operable to expand and/or contract the interbodyfusion device and a torque transfer mechanism operable to transfertorque to the driving mechanism in a direction non-parallel e.g.perpendicular to the driving mechanism. The interbody fusion device maybe a dual-axis adjustable interbody fusion device comprising a firstdriving mechanism and a second driving mechanism. The first drivingmechanism and the second driving mechanism can be operatedsimultaneously or independently by the torque transfer mechanism,allowing for simultaneous or independent control of the expansion and/orlordotic adjustment of the interbody fusion device. By way of example,an example interbody fusion device in a contracted configuration can beanteriorly inserted in the patient and placed between adjacentvertebrae, with the first driving mechanism of the interbody fusiondevice being positioned along the posterior side of the patient and andthe second driving mechanism of the interbody fusion device beingpositioned along the anterior side of the patient. The interbody fusiondevice can be then operated by applying torque anteriorly e.g. to afirst transfer mechanism, which is in a direction generallyperpendicular to the first driving mechanism that accepts the torquefrom the first transfer mechanism, in turn allowing the first drivingmechanism to convert the torque to a linear motion creating expansion ofthe interbody fusion on the posterior side, and a second transfermechanism, which is in a direction generally perpendicular to the seconddriving mechanism that accepts the torque from the second transfermechanism, in turn allowing the second driving mechanism to convert thetorque to a linear motion creating expansion of the interbody fusiondevice on the anterior side. These transfer and drive mechanisms allowthe intervertebral space at the posterior side and/or anterior side ofthe patient to be expanded and/or lordotically adjusted, simultaneouslyor independently, to achieve a desired sagittal balance or correctsagittal imbalance for the patient. While kyphosis (negative lordosis)is not desirable in the lumbosacral segment of the spine, the interbodyfusion device of the disclosure can be kyphotically adjusted (negativelordosis) if desired.

With reference to FIGS. 1A-1D, an example interbody fusion device 100may comprise an expandable housing 102, a first driving mechanism 200, asecond driving mechanism 250, and a torque transfer mechanism 300. Thefirst driving mechanism 200 is arranged in the housing 102 at a firstlateral area 104 operable to expand and/or contract the housing at thefirst lateral area 104. The second drive mechanism 250 is arranged inthe housing 102 at a second lateral area 106 operable to expand and/orcontract the housing at the second lateral area 106. The torque transfermechanism 300 is operable to receive torque in a direction non-parallel,e.g. generally perpendicular to the first driving mechanism 200 and thesecond driving mechanism 250 and transfer torque to the first drivingmechanism 200 and the second driving mechanism 250. As will be describedin greater detail below, the torque transfer mechanism 300 can transmitor translate torque to the first driving mechanism 200 and the seconddriving mechanism 250 simultaneously or independently, allowingexpansion and/or contraction of the housing 102 at the first lateralarea 104 and the second lateral area 106 to be controlled simultaneouslyor independently.

With reference to FIGS. 1A-1D, the housing 102 may include a first orinferior shell member 110 and a second or superior shell member 120. Theinferior shell member 110 and the superior shell member 120 may includeone or more openings or windows for accepting bone graft material orallowing bone to pass as fusion occurs. The sides or edges of theinferior member 110 and the superior shell member 120 may includechamfered or rounded portions to facilitate insertion of the interbodyfusion device 100 into the patient's anatomy. The surfaces of theinferior shell member 110 and the superior shell member 120 may includevarious features such as serrations, teeth, recesses, dents, etc. tohelp prevent migration of the device or provide better hold. Thesurfaces of the inferior shell member 110 and the superior shell member120 may also include countersink hole features to accept various typesof anchors to also help prevent migration and/or further stabilizationof the device.

The inferior shell member 110 may include a plurality of individualriser members 112 (FIG. 1D). The superior shell member 120 may include aplurality of individual riser members 122 (FIG. 1D). The plurality ofindividual riser members 112 of the inferior shell member 110 and theplurality of individual riser members 122 of the superior shell members120 may define a first step tracking run 113 along a first lateral area104 of the housing 102 and a second step tracking run 123 along a secondlateral area 106 of the housing 102 (FIG. 1D). The height of theplurality of individual riser members 112, 122 may change along thefirst step tracking run 113 and the second step tracking run 123. Forexample, the height of the plurality of individual riser members 112,122 of the first and second step tracking runs 113, 123 may increasesuccessively from a central portion of the step tracking extendingdistally from the central portion.

With reference to FIGS. 1A-1D, the first driving mechanism 200 mayinclude a first shaft or axle 202 having a longitudinal axis and a firstpair of screw members 220, 222. The second driving mechanism 250 mayinclude a second shaft or axle 252 having a longitudinal axis and asecond pair of screw members 270, 272. The first axle 202 may bearranged at a first lateral area 104 of the housing 102. The second axle252 may be arranged at the second lateral side 106 of the housing 102.The first axle 202 and the second axle 252 may be substantiallyparallel.

The first pair of screw members 220, 222 may each be provided with athrough-opening configured to allow the first axle 202 to pass andengage with the first pair of screw members 220, 222. The second pair ofscrew members 270, 272 may each be provided with a through-openingconfigured to allow the second axle 252 to pass and engage with thesecond pair of screw members 220, 222. The second axle 252 may comprisetwo separate sections 254 and 256 that are assembled, to be describedfurther below. The rotation of the first axle 202 causes the first pairof screw members 220, 222 to rotate and travel on the first steptracking run 113 defined by the individual riser members 112, 122 on theinferior and superior shell members 110, 120, converting the rotationalmotion into linear motion. The rotation of the second axle 252 causesthe second pair of screw members 270, 272 to rotate and travel on thesecond step tracking run 123 defined by the individual riser members112, 122 on the inferior and superior shell members 110, 120, convertingthe rotational motion into linear motion. In response to the linearmovement of the first pair of screw members 220, 222 as they advancealong and on the individual on the individual risers 112, 122, theinferior shell member 110 and the superior shell member 120 movelinearly relative to each other, effecting expansion or contraction ofthe housing 102 at the first lateral area 104. Likewise, in response tothe linear movement of the second pairs of screw members 270, 272 asthey advance along and on the individual risers 112, 122, the inferiorshell member 110 and the superior shell member 120 move linearlyrelative to each other, effecting expansion or contraction of thehousing 102 at the second lateral area 106. As will be described ingreater detail below, the first axle 202 and the second axle 252 can beoperated or rotated by the torque transfer mechanism 300 simultaneouslyand independently. Therefore, a degree of expansion or contraction ofthe housing 102 at the first lateral area 104 can be simultaneously orindependently adjusted relative to a degree of expansion or contractionof the housing 102 at the second lateral area 106 when the first pair ofscrew members 220, 222 and the second pair of screw members 270, 272 arerotated to different positions on the first tracking run 113 and secondstep tracking run 123.

The first pair of screw members 220, 222 may be configured and/orarranged such that the directional orientation of the helical thread ofthe screw member 220 is opposite to the directional orientation of thescrew member 222 so that the screw members 220, 222 of the first pairmove in an opposite direction relative to each other upon rotation ofthe first axle 202. Similarly, the second pair of screw members 270, 272may be configured and/or arranged such that the directional orientationof the helical thread of the screw member 270 is opposite to thedirectional orientation of the helical thread of the screw member 272 sothat the screw members of the second pair move in an opposite directionrelative to each other upon rotation of the second axle 252.

The first pair of screw members 220, 222 and the second pair of screwmembers 270, 272 may each have a tapered configuration and comprise aroot surface and a helical thread. The root surface of a screw membermay provide a contact surface for a riser member. The helical thread ofa screw member can be configured to be received in the gap betweenadjacent riser members. The first pair of screw members 220, 222 and thesecond pair of screw members 270, 272 may each have a variable rootradius and/or a helical thread with a variable thickness that aresimilar or different in size with respect to one another. A variableroot radius and thread thickness can create a tighter fit between thescrew members and the individual riser members, which in turn reduces,minimizes, or eliminates unwanted micro-motion between parts when theinterbody fusion device is in its starting position, expanded positionor lordotically adjusted position. Various embodiments of screw membersare described in U.S. Pat. Nos. 9,889,019, 10,188,527, and U.S.application Ser. No. 16/569,621 filed Sep. 12, 2019 entitled “Expandableand Adjustable Lordosis Interbody Fusion System.” The disclosures ofU.S. Pat. Nos. 9,889,019 and 10,188,527, and U.S. Ser. No. 16/569,621are incorporated herein by reference in their entirety.

The positions of the plurality of individual riser members 112 on theinferior shell member 110 may arrange to offset from the positions ofthe plurality of individual riser members 122 on the superior shellmember 120 so that the plurality of individual riser members 112 of theinferior shell member 110 may intermesh the plurality of individualriser members 122 of the superior shell member 120 when the interbodyfusion device 100 is in a contraction configuration.

With reference to FIGS. 1A-1D, the torque transfer mechanism 300 allowsfor application of torque to the first driving mechanism 200 and thesecond driving mechanism 250 in a direction non-parallel e.g. generallyperpendicular to the longitudinal axis of the first axle 202 of thefirst driving mechanism 200 or the longitudinal axis of the second axle252 of the second driving mechanism 250. As better viewed in FIG. 1C,the torque transfer mechanism 300 may include a first gear assembly 310operable to receive and transfer torque to the first driving mechanism200, and a second gear assembly 350 operable to receive and transfertorque to the second driving mechanism 250.

The first gear assembly 310 may include a translating gear 312 and adriving gear 314. The translating gear 312 may be coupled or fixedlycoupled to the first axle 202 of the first driving mechanism 200. Thefirst axle 202 may be a single component or comprise two separatesections that are press-fit and/or welded together to form a singlecomponent. The translating gear 312 may be configured to receive torquefrom the driving gear 314 and rotate, causing the first axle 202 torotate. The rotation of the first axle 202 causes the first pair ofscrew members 220, 222 to rotate and move on the individual risermembers, causing the first and second shell members 110, 120 to movelinearly relative to each other thereby expanding and/or contracting thehousing 102 at the first lateral area 104. The driving gear 314 may beconfigured to receive torque applied in a direction non-parallel e.g.generally perpendicular to the first axle 202, and transfer torque tothe translating gear 312. As shown, the driving gear 314 may be coupledto the first axle 202 via a connection member 316 (FIGS. 1C and 1D). Forexample, the connection member 316 may comprise a ring 318 received on arounded portion of the first axle 202, and an arm 320 extended from thering 318 and received in the driving gear 314. The arm 320 may bethreaded or unthreaded to allow the driving gear 314 to rotate about theaxes of the arm 320 of the connection member 316 and restrict off axismotion while transferring torque to the translating gear 312. Thedriving gear 314 may have an elongate portion 322 configured to berotatably received in a sleeve section of a driving gear in the secondgear assembly 350 (FIG. 1D), to be described in greater detail below.The end of elongate portion 322 of the driving gear 314 of the firstgear assembly 310 may be provided with a feature e.g. a female hexalobe324 for engaging with a driver in a surgical instrument to be describedin greater detail below.

The translating gear 312 and the driving gear 314 of the first gearassembly 310 may be various types of bevel gears such as straight,spiral, zerol bevel, hypoid, or spiroid. By way of example, thetranslating gear 312 and the driving gear 314 may have a pitch e.g. 8mm. Other gear sizes are apparently possible, and the present claims arenot so limited. In certain embodiments, the principle of the disclosurecan be implemented with worm gears.

The second gear assembly 350 may include a first translating gear 352and a first driving gear 354. The second gear assembly 350 may furtherinclude a second translating gear 362 and a second driving gear 364. Incertain embodiments of the disclosure, the second axle 252 may include afirst section 254 operating with a screw member 270 and a second section256 operating with a screw member 272. Therefore, the first translatinggear 352 of the second gear assembly 350 may be coupled to the firstsection 254 of the second axle 252 and configured to rotate the firstsection 254. Rotation of the first section 254 of the second axle 252causes the screw member 270 to rotate and travel on the individual risermembers. The second translating gear 262 of the second gear assembly 350may be coupled to the second section 256 of the second axle 252 andconfigured to rotate the second section 256. Rotation of the secondsection 256 of the second axle 252 causes the screw member 272 to rotateand travel along and on the individual riser members. The first section254 and the second section 256 of the second axle 252 may be rotatablyconnected to a connection member 370. For example, the connection member370 may comprise a ring 372, a first arm (not shown) extended from thering and received in the first section 254 of the second axle 252, and asecond arm (not shown) extended from the ring and received in the secondsection 256 of the second axle 252. The first arm and the second arm maybe threaded or unthreaded to allow the first section 254 and the secondsection 256 of the second axle 252 to rotate respectively about the axesof the connection member 370 first arm and second arm while restrictingoff axis motion.

The first driving gear 354 of the second gear assembly 350 may beconfigured to receive torque applied in a direction non-parallel e.g.generally perpendicular to the second axle 352, and transfer torque tothe first translating gear 352 of the second gear assembly 350. Thesecond driving gear 364 of the second gear assembly 350 may beconfigured to receive torque applied in a direction non-parallel e.g.generally perpendicular to the second axle 252, and transfer torque tothe second translating gear 362 of the second gear assembly 350. Forexample, the first driving gear 354 may include a feature e.g. a femalehexalobe 355 configured to engage with a driver in a surgical instrumentfor receiving torque in a direction generally perpendicular to thesecond axle 252. In certain embodiments, the first driving gear 354 andthe second driving gear 364 of the second gear assembly 350 may beconstructed or assembled to operate as a single unit such that arotation of the first driving gear 354 allows a rotation of the seconddriving gear 364. For example, the first driving gear 354 and the seconddriving gear 364 may be connected to form a tubular section 374, whichmay be received in the ring 372 of the connection member 370, allowingthe first driving gear 354 and the second driving gear 364 to rotate asa single unit (FIG. 1D). Alternatively, the first driving gear 354 andthe second driving gear 364 may be disconnected to form a section with agap where the section 374 is present to allow for independent adjustmentin turn allowing for independent or unequal rotations of axle section254 and 256, allowing the screw members 270 and 272 to rotate and travelalong and on the individual riser members at different locations withrespect to one another.

The first driving gear 354 and the first translating gear 352 of thesecond gear assembly 350 may be various classifications and types ofbevel gears. The second driving gear 364 and the second translating gear362 of the second gear assembly 350 may be various classifications andtypes of bevel gears. The first driving gear 354 and the second drivinggear 364 may have a different pitch. For example, the first driving gear354 may have a pitch e.g. 8 mm and the second driving gear 364 may havea pitch e.g. 6 mm. As such, the first translating gear 352 may have apitch e.g. 8 mm and the second translating gear 362 may have a pitche.g. 6 mm. Other gear sizes are apparently possible and the presentclaims are not so limited. Alternatively, the first driving gear 354 andthe second driving gear 364 may have a same pitch, and the firsttranslating gear 352 and the second translating gear 362 may have a samepitch. In certain embodiments, the principle of the disclosure can beimplemented with worm gears.

In certain embodiments, the torque transfer mechanism 300 can beconfigured to allow a surgical instrument to operate the first gearassembly 310 and the second gear assembly 350, either simultaneously orindependently. As better viewed in FIGS. 1C and 1D, the driving gear 314of the first gear assembly 310 may include an elongate portion 322. Thesecond driving gear 364 of the second gear assembly 350 may include asleeve section 366. The elongate portion 322 of the driving gear 314 ofthe first gear assembly 310 can be rotatably received in the sleevesection 366 of the second driving gear 364 of the second gear assembly350. This allows a surgical instrument having two drivers, e.g. a malehexalobe driver within a female hexalobe driver, to operate the firstgear assembly 310 and the second gear assembly 350 simultaneously andindependently. As such, the first driving mechanism 200 and the seconddriving mechanism 250 of the interbody fusion device 100 can be operatedeither simultaneously or independently by the surgical instrument viathe first gear assembly 310 and the second gear assembly 350respectively. By way of example, the end of the elongate portion 322 ofthe driving gear 314 of the first gear assembly 310 may be provided witha feature 324 e.g. a female hexalobe for engaging with a first driverhaving e.g. a male hexalobe feature. The channels in the first drivinggear 354 and the second driving gear 364 including the sleeve section366 allow the first driver in the surgical instrument to access to thefemale hexalobe feature 324 in the driving gear 314 of the first gearassembly 310. The first driving gear 354 of the second gear assembly 350may be provided with a feature 355 e.g. a female hexalobe featureconfigured for engaging with a second driver having e.g. an externalhexalobe feature.

FIGS. 2A-2C show a surgical instrument 400 which can used in operatingan example interbody fusion device 100 of the disclosure. FIGS. 3A-3Dillustrate engagement of a surgical instrument 400 with an exampledual-axis interbody fusion device 100 of the disclosure. Variousoperating modes can be achieved through different optional adjustmentcombinations of the two axes of the interbody fusion device thatcorrelate with two directions of the body perpendicular to the twodesired directions of the body expansion and/or contraction of theinterbody fusion device is desired. For example, adjusting the posteriorand anterior axes simultaneously or independently to create expansion inthe superior and inferior directions equally or unequally of theinterbody fusion device respectively. As better viewed in FIG. 3A-3D,the surgical instrument 400 may include a first driver 410 and a seconddriver 420. The first driver 410 may be rotatably received in a channelin the second driver 420, and can be extended out and retracted into thechannel in the second driver 420, allowing the first driver 410 to applytorque independently of or simultaneously with the second driver 420.The first driver 410 of the surgical instrument 400 may include aworking end portion having a feature e.g. a male hexalobe for engagingwith the driving gear 314 of the first gear assembly 310 which mayinclude an end having a feature e.g. the female hexalobe. The seconddriver 420 of the surgical instrument 400 may include a working endportion having a feature e.g. an external hexalobe feature for engagingthe first driving gear 354 of the second gear assembly 350 which mayhave a feature e.g. a female hexalobe.

With reference to FIG. 3B, the first driver 410 of the surgicalinstrument 400 can be extended to allow the first driver 410 to engagethe driving gear 314 of the first gear assembly 310, and the seconddriver 420 to engage the first driving gear 354 of the second gearassembly 350. Operating or turning the first driver 410 and the seconddriver 420 of the surgical instrument 400 simultaneously allowsapplication of torque to the first gear assembly 310 and the second gearassembly 350 simultaneously, which in turn transfer torque to or actuatethe first driving mechanism 200 and the second driving mechanism 250 ofthe interbody fusion device 100 simultaneously, effecting expansion orcontraction of the interbody fusion device 100 at both the posteriorside 104 and the anterior side 106. With reference FIG. 3C, the firstdriver 410 of the surgical instrument 400 may be retracted to disengagethe driving gear 314 of the first gear assembly 310, allowing only thesecond driver 420 of the surgical instrument 400 to engage the firstdriving gear 354 of the second gear assembly 350. Operating or turningthe second driver 420 of the surgical instrument 400 allows applicationof torque to the second gear assembly 350 only, which in turn transfertorque to or actuate the second driving mechanism 250 of the interbodyfusion device 100 only, thereby effecting expansion or contraction ofthe interbody fusion device 100 at the anterior side 106. With referenceto FIG. 3D, the first driver 410 of the surgical instrument 400 may beextended to engage the driving gear 314 of the first gear assembly 310,and the second driver 420 of the surgical instrument 400 may beretracted to disengage the first driving gear 354 of the second gearassembly 350. Operating or turning the first driver 410 of the surgicalinstrument 400 allows application of torque to the first gear assembly310 only, which in turn transfer torque to or actuate the first drivingmechanism 200 of the interbody fusion device 100 only, thereby effectingexpansion or contraction of the interbody fusion device 100 at theposterior side 104.

Returning to FIG. 1C, the interbody fusion device 100 may include afirst thrust bearing 105 coupling the first axle 202 and the second axle252 at a first end of the first axle 202 and a first end of the secondaxle 252. Additionally, or alternatively, the interbody fusion device100 may include a second thrust bearing 107 coupling the first axle 202and the second axle 252 at a second end of the first axle 202 and asecond end of the second axle 202. The first thrust bearing 105 and/orthe second thrust bearing 107 may be constructed to include two pieces,which can join together by e.g. press fit and/or welding. The firstthrust bearing 105 and/or the second thrust bearing 107 allow the firstaxle 202 rotate about the longitudinal axis of the first axle andprohibit translational or linear movement of the first axle. Likewise,the first thrust bearing 105 and/or the second thrust bearing 107 allowthe first section 254 and the second section 255 of the second axle 252to rotate about the longitudinal axis of the second axle and prohibittranslational or linear movement of the first section 254 and the secondsection 256 of the second axle 252.

The interbody fusion device 100 or at least a part of the interbodyfusion device 100 may be constructed from a material comprising metalsuch as titanium, tantalum, stainless steel, cobalt chrome, or any otherbiocompatible metal, or alloy. The interbody fusion device 100 or a partof the interbody fusion device 100 may also be constructed from apolymeric material such as poly-ether-ether-ketone (PEEK),poly-ether-ketone-ketone (PEKK), poly-ether-ketone (PEK), and so on.

The interbody fusion device 100 can be in any size suitable for spinalfusion procedures. By way of example, the distance from an end toanother end of the device 100 along the first or second drivingmechanism 200, 250 (“length”) may range from 25 to 60 millimeters (mm).The distance from one lateral side of the device to the opposite lateralside (“width”) may range from 20 mm to 35 mm. The device may bemanufactured in numerous offerings with different lengths and widths invarious increments, for example, 2 mm increments in width and 5 mmincrements in length. The distance from the inferior shell membersurface to the superior shell member surface of the interbody fusiondevice in a fully contracted configuration (“base height”) may rangefrom 5 mm to 10 mm. The interbody fusion device may have different baseheights or starting heights at the anterior side and the posterior side.For example, the base height at the posterior side may be smaller thanthe base height at the anterior side to accommodate to the nature of theanterior surgery to allow for a deeper device to fit into theintervertebral space, as shown in FIG. 2C. A contracted configurationwith different starting heights at the posterior side and the anteriorside may also help prevent against device subsidence and better meet theanatomy of the human spine. Alternatively, the interbody fusion device100 may have a same or similar base height at both the anterior side andthe posterior side. The dual-axis driving mechanisms according toembodiments of the disclosure can provide a continuous expansion inheight ranging from 0 mm to 9 mm and a continuous angulation between theinferior and superior shell member surfaces (“lordosis”) ranging from0-30 degrees. It should be noted that the above specific dimensions areprovided for thorough understanding of various aspects of the disclosurebut are not intended to limit the scope of the claims. Other dimensionsare apparently possible to one of ordinary skill.

Example 1: Expansion Mode (Simultaneous Dual-Axis Adjustments)

With reference to FIGS. 4 and 1C, an expansion mode of an exampleinterbody fusion device 100 will now be described. In the expansionmode, the first driving mechanism 200 and the second driving mechanism250 of the interbody fusion device 100 can be operated simultaneously,providing parallel expansion or contraction of the interbody fusiondevice 100.

The interbody fusion device 100 in a starting or contractedconfiguration can be first placed in the intervertebral space via ananterior surgical procedure. To begin with the expansion mode, the usermay use a surgical instrument 400 including a first driver 410 and thesecond driver 420 as shown in FIGS. 2A-2C and 3A-3D, allowing the firstdriver 410 to engage the driving gear 314 of the first gear assembly310, and the second driver 420 to engage the first driving gear 354 ofthe second gear assembly 350, as better shown in FIG. 3B. The user maythen apply torque in a direction generally perpendicular to the drivingmechanisms 200, 250 of the interbody fusion device 100, by turning boththe first driver 410 and the second driver 420 of the surgicalinstrument 400, e.g. in the clockwise direction, as indicated by arrowA1 and arrow A2 in FIG. 4.

With reference to FIGS. 4 and 1C, the turning of the first driver 410 ofthe surgical instrument 400 causes the driving gear 314 of the firstgear assembly 310 to rotate e.g. in the clockwise direction as indicatedby arrow B1, which in turn drives the translating gear 312 e.g. in theoutward direction as indicated by arrow B2, causing the first axle 202to rotate e.g. in the outward direction as indicated by arrow B2. Therotation of the first axle 202 causes the screw members 220, 222 totravel on the riser members e.g. in the outward directions as indicatedby arrow B3, causing the inferior shell member 110 and the superiorshell member 120 of the interbody fusion device 100 to move linearlyrelative to each other, e.g. expand, at the posterior side 104 asindicated by arrow B4.

With reference to FIGS. 4 and 1C, the turning of the second driver 420of the surgical instrument 400 causes the first driving gear 354 of thesecond gear assembly 350 to rotate e.g. in the clockwise direction, asindicated by arrow C1, which in turn drives the first translating gear352 e.g. in the outward direction as indicated by arrow C2, causing thefirst section 254 of the second axle 252 to rotate e.g. in the outwarddirection as indicated by arrow C2. The rotation of the first section254 of the second axle 252 causes the screw member 270 to travel on theriser members e.g. in the outward direction as indicated by arrow C3.

Still with reference to FIGS. 4 and 1C, the turning of the second driver420 of the surgical instrument 400 also causes the second driving gear364 of the second gear assembly 350 to rotate e.g. in the clockwisedirection, as indicated by arrow D1, which in turn drives the secondtranslating gear 362 e.g. in the outward direction as indicated by arrowD2, causing the second section 256 of the second axle 252 to rotate e.g.in the outward direction as indicated by arrow D2. The rotation of thesecond section 256 of the second axle 252 causes the screw member 272 totravel on the riser members e.g. in the outward direction as indicatedby arrow D3.

The movement of the screw member 270 on the first section 254 of thesecond axle 252 and the screw member 272 on the second section 256 ofthe second axle 252 causes the inferior shell member 110 and superiorshell member 120 to move linearly relative to each other, e.g. expand,at the anterior side as indicated by arrow D4.

It should be noted that while the operations of the driving gear 314 andtranslation gear 312 of the first gear assembly 310, the first drivinggear 354 and second driving gear 364 of the second gear assembly 350,the first translating gear 352 and the second translating gear 362 ofthe second gear assembly 350, and first driving mechanism 200 and seconddriving mechanism 250 are described in sequential steps for clarity, therotation, translation, or movement of the above assemblies, mechanismsor parts of the mechanisms occur simultaneously upon turning the firstdriver 410 and the second driver 420 of the surgical instrument 400simultaneously. The example illustrated in FIG. 4 expands the interbodyfusion device 100 at both the posterior side 104 and the anterior side106 by turning the first driver 410 and the second driver 420 of thesurgical instrument 400 simultaneously e.g. in the clockwise direction.A reverse operation by turning the first driver 410 and the seconddriver 420 in the counterclockwise direction may contract the interbodyfusion device 100 from the expanded configuration. FIG. 7 is anisometric view showing an expanded configuration of the interbody fusiondevice 100.

Example 2: Lordosis Mode (Independent Anterior Axis Adjustment)

With reference to FIGS. 5 and 1C, a lordosis mode, or independentadjustment of the anterior axis of an example interbody fusion device100 will now be described. In this lordosis mode, the second drivingmechanism 250 of an interbody fusion device 100 can be operatedindependently of the first driving mechanism 100, lordotically adjustingthe configuration of the interbody fusion device 100 at the anteriorside 106. A lordosis mode of the interbody fusion device 100 may bedesired to provide an offset in expansion between the anterior side 104and posterior side 106 of the interbody fusion device 100. The anteriorside 104 can be expanded and/or contracted to a point below theposterior side 106 resulting in negative lordosis (kyphosis).

To begin with the lordosis mode, the user may extend only the seconddriver 420 of the surgical instrument 400, allowing only the seconddriver 420 to engage with the first driving gear 354 of the second gearassembly 350, as shown in FIG. 3C. If the first driver 410 of thesurgical instrument 400 had been inserted across the entire span of theinterbody fusion device during the expansion mode, the first driver 410can be retracted to the point shown in FIG. 3C in order to operate onlythe anterior side 106 of the interbody fusion device 100 independently.A marking on the surgical instrument 400 can be provided to helpindicate how far the first driver 410 can be inserted in the interbodyfusion device 100 for the lordosis mode. Then, the user may apply torquein a direction generally perpendicular to the second driving mechanism250 of the interbody fusion device 100 by turning the second driver 420e.g. in the clockwise direction, as indicate by arrow E1.

With reference to FIGS. 5 and 1C, the turning the second driver 420 ofthe surgical instrument 400 causes the first driving gear 354 of thesecond gear assembly 350 to rotate e.g. in the clockwise direction asindicated by arrow F1, which in turn drives the first translating gear352 e.g. in the in the outward direction as indicated by arrow F2,causing the first section 254 of the second axle 252 to rotate e.g. inthe outward direction as indicated by arrow F2. The rotation of thefirst section 254 of the second axle 252 causes the screw member 270 totravel on the riser members e.g. in the outward direction as indicatedby arrow F3.

The turning the second driver 420 of the surgical instrument 400 alsocauses the second driving gear 364 of the second gear assembly 350 torotate e.g. in the clockwise direction as indicated by arrow G1, whichin turn drives the second translating gear 362 e.g. in the outwarddirection as indicated by arrow G2, causing the second section 256 ofthe second axle 252 to rotate e.g. in the outward direction as indicatedby arrow G2. The rotation of the second section 256 of the second axle252 causes the screw member 272 to travel on the riser members e.g. inthe outward direction as indicated by arrow G3. In certain embodiments,the first driving gear 354 and the second driving gear 364 can bemodified in which a gap between both components exists when assembled,with the first driving gear 354 having an increased overall diameter.The first driving gear female hexalobe mating geometry that mates withthe second driver 420 of the surgical instrument 400 may be modified toallow the second driver 420 to pass completely through the first drivinggear 354 and reach the second driving gear 364. This modified designconfiguration would allow for unequal expansion adjustments between thescrew member 270 and the screw member 272 across the coronal plane,allowing for corrections with patients possessing deformities such asscoliosis.

The movement of the screw members 270, 272 on the individual risermembers causes the first shell member 110 and the second shell member120 to linearly move relative to each other or expand at the anteriorside 106, lordotically adjusting the interbody fusion device 100 at theanterior side 106, as indicated by arrow H1. Completing all of thepreviously described movements of the components in the reversedirections to create a contracted adjustment of the anterior side 106 toa point below the posterior side 104, would kyphotically adjust(negative lordosis) the interbody fusion device 100.

It should be noted that while the operations of the first driving gear354 and second driving gear 364 of the second gear assembly 350, and thefirst translating gear 352 and the second translating gear 362 of thesecond gear assembly 350, and the second driving mechanism 250 aredescribed in sequential steps for clarity, the above assemblies,mechanisms or parts are operated simultaneously upon turning of thesecond driver 420 of the surgical instrument 400. Further, the exampleshown in FIG. 5 lordotically adjusts the interbody fusion body 100 orexpands the device at the anterior side 106 by turning the second driver420 of the surgical instrument 400 in the clockwise direction. Theinterbody device may also operate adequately if inverted or insertedinto the intervertebral disc space upside down. Correct operation of theinterbody device in this inverted position can be achieved by reversingthe applied torque and through rotating the second driver 420 e.g. inthe counterclockwise direction may adjust the degree of the lordosis ofthe interbody fusion device 100. FIG. 8 is an isometric view showing alordotically adjusted configuration of the interbody fusion device 100.

Example 3: Lordosis Mode (Independent Posterior Axis Adjustment)

With reference to FIGS. 6 and 1C, a further lordosis mode, orindependent adjustment of the posterior axis of an example interbodyfusion device 100 will now be described. In the lordosis mode, the firstdriving mechanism 200 of the interbody fusion device 100 can be operatedindependently of the second driving mechanism 250, lordoticallyadjusting the configuration of the interbody fusion device 100 at theposterior side 104. The posterior side 104 can be expanded to a pointabove the anterior side 106 resulting in negative lordosis (kyphosis).

To begin with the lordosis mode, the user may extend only the firstdriver 410 of the surgical instrument 400, allowing only the firstdriver 410 to engage the driving gear 314 of the first gear assembly310, as shown in FIG. 3D. In this lordosis mode, the second first driver420 of the surgical instrument 400 does not engage the first drivinggear 354 of the second gear assembly 350. Then, the user may applytorque to in a direction generally perpendicular to the first drivingmechanism 200 of the interbody fusion device 100 by turning the firstdriver 410 e.g. in the clockwise direction, as indicate by arrow 11.

With reference to FIGS. 6 and 1C, the turning the first driver 410 ofthe surgical instrument 400 causes the driving gear 314 of the firstgear assembly 310 to rotate e.g. in the clockwise direction as indicatedby arrow J1, which in turn drives the translating gear 312 e.g. in theoutward direction as indicated by arrow J2, causing the first axle 202to rotate e.g. in the outward direction as indicated by arrow J2. Therotation of the first axle 202 causes the screw members 220, 222 totravel on the riser members e.g. in the outward direction as indicatedby arrow J3.

The movement of the riser members 220, 222 on the individual risermembers causes the first shell member 110 and the second shell member120 to move linearly relative to each other or expand at the posteriorside 104, lordotically adjusting the interbody fusion device 100 at theposterior side 104, as indicated by arrow K1. Completing expansion ofthe posterior side 104 to a point of adjustment above the anterior side106 would kyphotically adjust (negative lordosis) the interbody fusiondevice 100.

It should be noted that while the operations of the driving gear 314 andthe translating gear 312 of the first gear assembly 310, and the firstdriving mechanism 20 are described in sequential steps for clarity, therotation, translation, or movement of the above assemblies, mechanismsor parts occur simultaneously upon turning of the first driver 410 ofthe surgical instrument 400. Further, the example shown in FIG. 6lordotically adjusts the interbody fusion device 100 at the posteriorside 104 by turning the first driver 410 of the surgical instrument 400in the clockwise direction. A reverse operation by turning the firstdriver 410 e.g. in the counterclockwise direction may adjust the degreeof the lordosis of the interbody fusion device 100.

FIGS. 9A-9B show an example interbody fusion device 100 placed inadjacent intervertebral bodies 452, 452, and expanded and/orlordotically adjusted according to embodiments of the disclosure.

With reference now to FIGS. 10A-14C, embodiments of the interbody fusiondevice 100 may include a fixation assembly 500, which can secure theinterbody fusion device 100 in the intervertebral space to preventunwanted lateral or medial migration of the interbody fusion device 100and prohibit the interbody fusion device 100 from unwinding or backingdown following adjustment.

As shown in FIGS. 10A-10B, the fixation assembly 500 in generalcomprises a plate assembly 510 and fasteners 512. The plate assembly 510is configured to be attachable to the interbody fusion device 100. Theplate assembly 510 comprises a plate member 511 provided with apertures514 configured for insertion of the fasteners 512 therethrough to secureto an inferior vertebral body and a superior vertebral bodyrespectively. The plate assembly 510 may also include fastener-lockmechanisms 520 to prevent fasteners from backing out of the vertebralbodies. While four apertures 514 in the plate member 511 and fourfasteners 512 are shown, other embodiments may include fewer or morethan four apertures in the plate member 511. Likewise, while fourfastener-lock mechanisms 520 are shown, other embodiments may includefewer or more than four fastener-lock mechanisms. Further, FIG. 10Bdepicts an assembled view where the plate assembly 510 is attached tothe interbody fusion device 100. It should be noted that in use, theplate assembly 510 can be attached to the interbody fusion device 100 insitu, or when the interbody fusion device 100 has been inserted in thepatient and placed between adjacent vertebral bodies. FIGS. 14A-14Bshows attaching of a plate assembly 510 to an interbody fusion device100 after the interbody fusion device 100 has been placed, expanded,and/or lordotically adjusted to a proper configuration between adjacentvertebrae. If desired, the plate assembly 510 may also be attached tothe interbody fusion device 100 prior to implantation of the interbodyfusion device.

In certain embodiments, the plate member 511 may be constructed from amaterial having sufficient strength such as titanium, stainless steel orother metal or alloy to provide orthotic support or supplementalfixation in addition to preventing migration or unwinding of theinterbody fusion device 100. As used herein, the term “supplementalfixation” refers to an embodiment of the fixation plate serving as anorthotic capable of holding adjacent vertebrae in place or immobilizingmovement of adjacent vertebrae until arthrodesis (bony fusion) takesplace.

With reference to FIG. 11, the plate member 511 may generally in anH-beam shape or a bone shape, with cutouts in the sides to minimize orreduce the profile of the plate. For example, the plate member 511 mayhave a reduced dimension in the middle portion as compared to the upperand lower portions of the plate member 511. The apertures 514 may beprovided in the upper and lower portions of the plate member 511. Areduced or optimized profile of the plate assembly 510 allows forimproved visualization of the interbody fusion device 100 inside thepatient especially e.g. in an anterior view. A reduced profile of theplate assembly 510 also facilitates insertion and placement of the plateassembly 510 in the patient anatomy. Other suitable size and shape ofthe fixation plate are possible, and the present claims are not solimited. The plate member 511 may include a geometry feature 516 e.g. anannular geometry feature provided with threading for connecting with asurgical instrument.

With reference to FIG. 11, the locations of the apertures 514 in theplate member 511 may be spaced apart as shown to allow the fasteners 512to be inserted through and directed to an inferior vertebral body and asuperior vertebral body respectively. An aperture 514 in the platemember 511 may be angled e.g. at 0-15 degrees with respect to areference plane perpendicular to a surface of the plate member 511. Anangled aperture allows for an angled trajectory of a fastener insertedthrough the aperture, as better viewed in FIG. 10B, providing for anoptimal angle for the fastener to anchor to a vertebral body. Furtherthe plate member 511 may possess a curved or non-parallel profilegeometry that exists at the location of the apertures in relation to themiddle body section to allow for even further angled trajectory offasteners above 15 degrees for even more optimal cortical bone purchase.An aperture 514 may include a counterbore or countersink portionconfigured for receiving the head of the fastener 512. The head of thefasteners 512 may have a spherical shape as shown FIG. 10A or any othersuitable shapes such as tapered or cylindrical shape to facilitate orallow for fastener trajectory adjustment. Examples of fasteners includebut are not limited to spinal expansion head screws, spinal lockingscrews, spinal self-locking screws, spinal shaft screws, spinal nails,spinal barbs, spinal hooks, or other threaded or non-threaded memberswhich can be anchored to a vertebral body.

With reference to FIG. 11, the plate assembly 510 may include at leastone fastener-lock mechanism 520 configured to prevent a fastener frombacking out. In FIG. 11, four fastener-lock mechanisms 520 are provided,each being located adjacent to an aperture 514 in the plate member 511.An example fastener-lock mechanism 520 may include a lock rod 522received in a recess 524 adjacent to an aperture 514 in the plate member511, and an adapter 526 welded or attached to an end of the lock rod 522to retain the lock rod 522 in the recess 524 and allow the lock rod 522to turn. The head of the lock rod 522 may have a rounded side portion522 a, a flat side portion 522 b, and an end 522 c provided with afeature such as a female hexalobe to receive a driver for engaging thelock mechanism 520. When the lock rod 522 is turned to set the lockmechanism 520 to an unlocked or open state, the head flat side portion522 b faces the aperture 514 in the plate member 511, leaving theaperture 514 open to allow a fastener 512 to insert through. After thefastener 512 is driven all the way through into a vertebral body and thefastener head received in the countersink of the aperture, the lock rod522 can be turned to set the lock mechanism 520 in a locked state, wherethe head rounded side portion 522 a extends over at least a portion ofthe aperture 514 or over the fastener 512, prohibiting the fastener 512from backing out. The lock mechanism 520 of the disclosure allows quick“one-step” locking, requiring only one turn of the lock rod 522 with adriver to lock or unlock the fastener 512. The use of a “one-step”locking mechanism can also simplify or reduce the profile of the plateassembly 510, which is beneficial for inserting and placing theapparatus in the patient anatomy.

With reference to FIGS. 12A-12B and 13A-13B, the plate assembly 510 mayinclude a geometry feature or features configured for attachment to theinterbody fusion device 100. The plate assembly 510 may include a malegeometry feature extended from the plate member configured to beinserted into a female geometry feature in a driving gear of the firstgear assembly 310 and/or the second gear assembly 350. FIGS. 12A-12Bshow a plate assembly 510 including a male geometry 530 e.g. a malehexalobe configured to be tightly mated into the female hexalobe 355 inthe first driving gear 354 of the second gear assembly 350. Once theplate assembly 510 is inserted into the interbody fusion device 100 andfastened to the vertebral bodies, the male hexalobe 530 of the plateassembly 510 can prevent unwanted rotation of the first driving gear 354of the second gear assembly 350, serving as a secondary lock to preventunwinding or backing down following adjustment of the interbody fusiondevice 100. FIGS. 13A-13B show a plate assembly 510 including anelongate male geometry 532 e.g. a male hexalobe configured to passthrough the first driving gear 354 and the second driving gear 364 ofthe second gear assembly 350, and be tightly mated into the femalehexalobe 324 in the driving gear 314 of the first gear assembly 310.Once the plate assembly 510 is inserted into the interbody fusion device100 and fastened to the vertebral bodies, the elongate male hexalobe 532prevents unwanted rotation of the driving gear 314 of the first gearassembly 310, serving as a secondary lock to prevent unwinding orbacking down following adjustment of the interbody fusion device 100. Incertain embodiments of the disclosure, the plate assembly 510 mayinclude a first male geometry configured to be tightly mated into thefemale geometry in the driving gear 314 of the first gear assembly 310,and a second male geometry configured to be tightly mated into thefemale geometry in the first driving gear 354 of the second gearassembly 350. For example as shown in FIG. 13B, the plate assembly 510may include a first male geometry 532 e.g. an elongate male hexalobeconfigured to be tightly mated into the female hexalobe 324 in thedriving gear 314 of the first gear assembly 310, and a second malegeometry 530 e.g. a male hexalobe configured to be tightly mated intothe female hexalobe 355 in the first driving gear 354 of the second gearassembly 350.

U.S. application Ser. No. ______ entitled “Dual Axis Adjustable SpinalSystems and Interbody Fusion Devices with Fixation” filed concurrentlywith this application, describes various embodiments of fixationassemblies for interbody fusion devices and spinal systems, thedisclosure of all of which is incorporated herein by reference in itsentirety.

With reference to FIGS. 14A-14C, in use, the plate assembly 510 can beinserted and attached to an interbody fusion device 100 in situ. Forinstance, an interbody fusion device 100 in a contracted configurationcan be first inserted and placed between adjacent vertebrae 452, 454 viaan anterior lumbar interbody fusion (ALIF) procedure, or any othersuitable surgical procedures. The interbody fusion device 100 can beexpanded and/or lordotically adjusted using a surgical instrument 400,forming a suitable configuration between the adjacent vertebrae 452,454, as described above in conjunction with FIGS. 3-6.

Then, the plate assembly 510 can be introduced to the target area, viathe same surgical approach for inserting and placing the interbodyfusion device 100, and attached to the interbody fusion device 100.According to embodiments of the disclosure, the surgical instrument 400used for placing and operating the interbody fusion device 100 can beused for inserting and attaching the plate assembly 510. By way ofexample, the surgeon can connect the plate assembly 510 to the surgicalinstrument 400 via the thread on the annular geometry feature 516 in theplate member 511, introduce the plate assembly 510 to the target areavia the same surgical approach, and insert the plate assembly 510 to theinterbody fusion device 100, as shown in FIG. 14A.

Fasteners 512 e.g. spinal screws can be then inserted through theapertures 514 in the plate member 511 and screwed into an inferiorvertebral body 452 and a superior vertebral body 454 respectively. Oncethe fasteners 512 are driven all the way, the fastener-lock mechanisms520 of the plate assembly 510 can be actuated using the surgicalinstrument 400 to lock the fasteners 512 to prevent them from backingout, as shown in FIG. 14B. The interbody fusion device 100 can be thenprevented from unwanted lateral or medial migration and unwinding orbacking down following expansion or lordotic adjustment, as shown inFIG. 14C.

Embodiments of an interbody fusion device are described in conjunctionwith FIGS. 1A-14C. Beneficially, embodiments of the interbody fusiondevice of the disclosure allow the surgeon to apply torque from theanterior direction perpendicularly that is then translated to that ofthe driving mechanisms responsible for expansion and lordotic adjustmentof the interbody fusion device. The dual-axis driving mechanisms allowsthe surgeon to adjust the height and unique level of lordosis to achievecomplete anatomical personalization for the patient. For example,embodiments of the interbody fusion device of the disclosure allows thesurgeon to set the interbody fusion device in fine configurations, toany unique height (e.g. 11.6 mm) and/or unique angle (e.g. 21.7°) neededfor the patient's spinal balance profile. Conventional techniques mayhave implants built at only a few predetermined lordotic configurationssuch as 20°, 25°, 30°.

The interbody fusion device can provide increased surgical efficiency.Conventionally, surgeons must perform impactful trialing, or sizing ofthe implant to determine the size of an implant needed for a specificpatient. According to embodiments of the disclosure, the interbodyfusion device can start at a smaller contracted height and then increasein height. This allows for streamlining or drastically reducing thetrialing process, which can in turn decrease the barbaric and roughimpact associated with the trialing process. The mechanism of theimplant also has enough space to distract the vertebral bodies back totheir normal desired positions. This control of distraction also takesout the need to distract using an extra instrument.

The use of a fixation assembly prevents the interbody fusion device fromunwanted lateral or medial migration and unwinding or backing downfollowing expansion or lordotic adjustment. The fixation plate can beconstructed with sufficient strength to provide orthotic support orsupplemental fixation. The fixation plate is implantable andconfigurable to attach to the interbody fusion device via a singlesurgical approach and patient position, thereby minimizing disruption tothe patient anatomy. The geometry such as the male geometries in thefixation plate can act as secondary safety locks for the interbodyfusion device, preventing the interbody fusion device from unwinding orbacking down following adjustment.

The interbody fusion device also provides benefits pertainingmanufacturing and hospital administration. It can reduce inventory.Currently an implant size must exist for every height, usually in 1 mmdegree increments, along with 5-degree increments of lordosis. Thisquickly makes the number of implants needed on hand very great. Theinterbody fusion device according to embodiments of the disclosure isfully adjustable, which ultimately cuts down on the number of implantsneeded in the operating room or needed to be held in in inventory.

All technical and scientific terms used herein have the meaning ascommonly understood by one of ordinary skill in the art unlessspecifically defined otherwise. As used in the description and appendedclaims, the singular forms of “a,” “an,” and “the” include pluralreferences unless the context clearly dictates otherwise. The term “or”refers to a nonexclusive “or” unless the context clearly dictatesotherwise. The term “first” or “second” is used to distinguish oneelement from another in describing various similar elements and shouldnot be construed as in any particular order unless the context clearlydictates otherwise.

Those skilled in the art will appreciate that various othermodifications may be made. All these or other variations andmodifications are contemplated by the inventors and within the scope ofthe invention.

1. An interbody fusion device, comprising: a housing comprising a firstshell member and a second shell member; a driving mechanism operable toexpand and/or contract the housing, the driving mechanism comprising anaxle having a longitudinal axis; a gear assembly operable to transfertorque to the driving mechanism, the gear assembly comprising a firsttranslating gear coupled to the axle and a first driving gear configuredto receive torque applied from a direction non-parallel to thelongitudinal axis of the axle and drive the first translating gear,whereby application of torque to the first driving gear causes the firsttranslating gear and the axle to rotate about the longitudinal axis,thereby actuating the driving mechanism to effect expansion and/orcontraction of the housing.
 2. The interbody fusion device of claim 1,wherein the first driving gear of the gear assembly is configured toreceive torque applied from the direction generally perpendicular to thelongitudinal axis of the axle.
 3. The interbody fusion device of claim2, wherein the driving mechanism further comprises a first screw memberand a second screw member, the first screw member and the second screwmember each having a through-opening adapted to allow the axle to pass;at least the first shell member comprises a plurality of riser membersfor receiving the first screw member and the second screw member; theaxle is engageable with the first screw member and the second screwmember, whereby rotation of the axle about the longitudinal axis causesthe first screw member and the second screw member to rotate with andtravels along the axle; and the first screw member and the second screwmember are engageable with the plurality of riser members, wherebyrotation of the first screw member and the second screw member causesthe first shell member and the second shell member to move relative toeach other to effect expansion and/or contraction of the housing.
 4. Theinterbody fusion device of claim 3, wherein the first screw member isdisposed at a first lateral side of the first translating gear, thesecond screw member is disposed at a second lateral side of the firsttranslating gear, and the first screw member and the second screw memberare configured to travel in opposition directions upon rotation of theaxle.
 5. The interbody fusion device of claim 1, wherein the axlecomprises a first section and a second section, the first section andthe second section of the axle being rotatably connected to a connectionmember, the first translating gear being coupled to the first section ofthe axle, and the gear assembly further comprises a second translatinggear coupled to the second section of the axle, and a second drivinggear configured to receive torque applied from the directionnon-parallel to the longitudinal axis of the axle and drive the secondtranslating gear, whereby application of torque to the second drivinggear causes the second translating gear and the second section of theaxle to rotate about the longitudinal axis.
 6. The interbody fusiondevice of claim 5, wherein the first driving gear and the second drivinggear of the gear assembly are configured to receive torque applied fromthe direction generally perpendicular to the longitudinal axis of theaxle.
 7. The interbody fusion device of claim 5, wherein the firstdriving gear has a first pitch and the second driving gear has a secondpitch different from the first pitch.
 8. The interbody fusion device ofclaim 5, wherein the first driving gear and the second driving gear areconnected via a tubular section and operate as a single unit.
 9. Theinterbody fusion device of claim 8, wherein the connection memberconnecting the first section and the second section of the axlecomprises a ring structure configured to receive the tubular section andallow the first driving gear and the second driving gear to rotate. 10.The interbody fusion device of claim 5, wherein the driving mechanismfurther comprises a first screw member and a second screw member, thefirst screw member having a through-opening adapted to allow the firstsection of the axle to pass, the second screw member having athrough-opening adapted to allow the second section of the axle to pass;at least the first shell member comprises a plurality of riser membersfor receiving the first screw member and the second screw member; thefirst section of the axle is engageable with the first screw member,whereby rotation of the first section of the axle about the longitudinalaxis causes the first screw member to rotate with and travels along thefirst section of the axle, the second section of the axle is engageablewith the second screw member, whereby rotation of the second section ofthe axle about the longitudinal axis causes the second screw member torotate with and travels along the second section of the axle; and thefirst screw member and the second screw member are engageable with theplurality of riser members, whereby rotation of the first screw memberand the second screw member causes the first shell member and the secondshell member to move relative to each other to effect expansion and/orcontraction of the housing.
 11. An interbody fusion device, comprising:a housing comprising a first shell member and a second shell member; afirst driving mechanism arranged in the housing at a first lateral area,a second driving mechanism arranged in the housing at a second lateralarea, the first driving mechanism comprising a first axle having alongitudinal axis, and the second driving mechanism comprising a secondaxle having a longitudinal axis; a first gear assembly operable totransmit torque to the first driving mechanism, the first gear assemblycomprising a translating gear coupled to the first axle and a drivinggear configured to receive torque applied from a direction non-parallelto the longitudinal axis of the first axle and drive the translatinggear, whereby application of torque to the driving gear causes thetranslating gear and the first axle to rotate about the longitudinalaxis of the first axle, thereby actuating the first driving mechanism toeffect expansion and/or contraction of the housing at the first lateralarea; and a second gear assembly operable to transmit torque to thesecond driving mechanism, the second gear assembly comprising at least afirst translating gear coupled to the second axle and a first drivinggear configured to receive torque applied from a direction non-parallelto the longitudinal axis of the second axle and drive the firsttranslating gear, whereby application of torque to the first drivinggear causes the first translating gear and the second axle to rotateabout the longitudinal axis of the second axle, thereby actuating thesecond driving mechanism to effect expansion and/or contraction of thehousing at the second lateral area.
 12. The interbody fusion device ofclaim 11, wherein the driving gear of the first gear assembly isconfigured to receive torque applied from the direction generallyperpendicular to the longitudinal axis of the first axle, and the firstdriving gear of the second gear assembly is configured to receive torqueapplied from the direction generally perpendicular to the longitudinalaxis of the second axle.
 13. The interbody fusion device of claim 11,wherein the first gear assembly and the second gear assembly aresimultaneously operable, whereby a degree of expansion and/orcontraction of the housing at the first lateral area and a degree ofexpansion and/or contraction of the housing at the second lateral areaare simultaneously adjustable.
 14. The interbody fusion device of claim11, wherein the first gear assembly is operable independently of thesecond gear assembly, whereby a degree of expansion and/or contractionof the housing at the first lateral area is independently adjustable,and/or the second gear assembly is operable independently of the firstgear assembly, whereby a degree of expansion and/or contraction of thehousing at the second lateral area is independently adjustable.
 15. Theinterbody fusion device of claim 11, wherein the second axle comprises afirst section and a second section, the first section and the secondsection each being rotatably connected to a connection member, the firsttranslating gear of the second gear assembly is coupled to the firstsection; the second gear assembly further comprises a second translatinggear coupled to the second section, and a second driving gear configuredto receive torque applied from the direction non-parallel to thelongitudinal axis of the second axle and drive the second translatinggear, whereby application of torque to the second driving gear causesthe second translating gear and the second section of the second axle torotate about the longitudinal axis of the second axle.
 16. The interbodyfusion device of claim 15, wherein the first driving gear and the seconddriving gear of the second gear assembly are operable as a single unit.17. The interbody fusion device of claim 16, wherein the first drivinggear and the second driving gear of the second gear assembly are coupledto form a tubular section; and the connection member rotatablyconnecting the first section and the second section of the second axlecomprises a ring structure configured to receive the tubular sectionallowing the first driving gear and the second driving gear to rotate.18. The interbody fusion device of claim 16, wherein the driving gear ofthe first gear assembly comprises an elongate portion, the seconddriving gear of the second gear assembly comprises a sleeve section, theelongate portion of the driving gear of the first gear assembly beingrotatably received in the sleeve section of the second driving gear ofthe second gear assembly, and the elongate portion of the driving gearof the first gear assembly comprises an end having a feature forengaging with a first driver of a surgical instrument, and the firstdriving gear of the second gear assembly comprises a feature forengaging with a second driver in the surgical instrument, therebyallowing the surgical instrument to operate the first gear assembly andthe second gear assembly simultaneously, or to operate the first gearassembly independently of the second gear assembly, or to operate thesecond gear assembly independently of the first gear assembly.
 19. Theinterbody fusion device of claim 15, wherein the first driving mechanismcomprises a first screw member and a second screw member, the firstscrew member and the second screw member of the first driving mechanismeach having a through-opening adapted to allow the first axle to pass;the second driving mechanism comprises a first screw member and a secondscrew member, the first screw member of the second driving mechanismhaving a through-opening adapted to allow the first section of thesecond axle to pass, the second screw member of the second drivingmechanism having a through-opening adapted to allow the second sectionof the second axle to pass; at least the first shell member comprises aplurality of riser members for receiving the first screw member and thesecond screw member of the first driving mechanism and the first screwmember and the second screw member of the second driving mechanism; thefirst axle of the first driving mechanism is engageable with the firstscrew member and the second screw member of the first driving mechanism,whereby rotation of the first axle of the first driving mechanism causesthe first screw member and the second screw member of the first drivingmechanism to rotate with and travels along the first axle of the firstdriving mechanism, causing the first shell member and the second shellmember to move relative to each other to effect expansion and/orcontraction of the housing at the first lateral area; and the firstsection of the second axle is engageable with the first screw member ofthe second driving mechanism, the second section of the second axle isengageable with the second screw member of the second driving mechanism,whereby rotation of the first section and the second section of thesecond axle causes the first screw member and the second screw member ofthe second driving mechanism to rotate with and travels along the firstsection and the second section of the second axle respectively, causingthe first shell member and the second shell member to move relative toeach other to effect expansion and/or contraction of the housing at thesecond lateral area.
 20. The interbody fusion device of claim 11,further comprising a first thrust bearing coupling the first axle andthe second axle at a first end of the first axle and a first end of thesecond axle; a second thrust bearing coupling the first axle and thesecond axle at a second end of the first axle and a second end of thesecond axle, wherein the first thrust bearing and the second thrustbearing are configured to allow the first axle and the second axle torotate about the longitudinal axis of the first axle and the second axlerespectively, and prohibit translational movement of the first axle andthe second axle respectively.
 21. The interbody fusion device of claim11, further comprising a fixation assembly for securing the interbodyfusion device in adjacent vertebral bodies, the fixation assemblycomprising a plate assembly, at least one first fastener and at leastone second fastener, wherein the plate assembly is configured to beattachable to the interbody fusion device and comprises a plate memberprovided with at least one first aperture for insertion of the at leastone first fastener therethrough to a first vertebral body and at leastone second aperture for insertion of the at least one second fastenertherethrough to a second vertebral body, thereby allowing the plateassembly to be attached to the interbody fusion device in situ andsecured to the first and second vertebral bodies.
 22. The interbodyfusion device of claim 11, wherein the plate assembly comprises a firstgeometry feature configured to mate a geometry feature in the drivinggear of the first gear assembly to prevent rotation of the driving gearof the first gear assembly relative to the fixation plate.
 23. Theinterbody fusion device of claim 22, wherein the plate assembly furthercomprises a second geometry feature configured to mate a geometryfeature in the first driving gear of the second gear assembly to preventrotation of the first driving gear of the second gear assembly relativeto the fixation plate.
 24. The interbody fusion device of claim 23,wherein the plate member constructed from a material having strengthcapable of providing supplemental fixation of the first and secondvertebral bodies.
 25. The interbody fusion device of claim 23, whereinthe plate assembly comprises a first fastener-lock mechanism configuredto prohibit the at least one first fastener from backing out of the atleast one first aperture, and a second fastener-lock mechanismconfigured to prohibit the at least one second fastener from backing outof the second aperture.